To be eligible for a flight engineer certificate, a person must --
(a) Be at least 21 years of age;
(b) Be able to read, speak, and understand the English language, or
have an appropriate limitation placed on his flight engineer certificate;
(c) Hold at least a second-class medical certificate issued under part
67 of this chapter within the 12 months before the date he applies, or
other evidence of medical qualification accepted for the issue of a flight
engineer certificate under §63.42; and
(d) Comply with the requirements of this subpart that apply to the
rating he seeks. (Sec. 6, 80 Stat. 937, 49 U.S.C. 1655)